Inhaled hydrogen ameliorates endotoxin-induced bowel dysfunction.

Aim: Gastrointestinal dysmotility frequently occurs during sepsis and multiple organ failure, remaining a major cause of morbidity and mortality in critically ill patients. Previous studies have shown that hydrogen, a new therapeutic gas, can improve various organ damage associated with sepsis. In this study, we investigated the protective efficacies of inhaled hydrogen against lipopolysaccharide (LPS)-induced ileus. Methods: Sepsis was induced in rats and mice by a single i.p. injection of LPS at 15 mg/kg for mice and 5 mg/kg for rats. Four groups of rats and mice including sham/air, sham/hydrogen, LPS/air, and LPS/hydrogen were analyzed. Hydrogen (1.3%) was inhaled for 25 h beginning at 1 h prior to LPS treatment. Gastrointestinal transit was quantified and cytokine levels, as well as neutrophil extravasation, in the intestinal muscularis propria were determined. Results: Lipopolysaccharide challenge remarkably delayed gastrointestinal transit of non-absorbable dextran, associated with increased leukocyte recruitment and upregulation of pro-inflammatory cytokine mRNA expressions in the muscularis propria. Hydrogen significantly prevented LPS-induced bowel dysmotility and reduced leukocyte extravasation, as well as inhibition of inflammatory cytokine expression. Conclusions: This study showed the protective effects of hydrogen inhalation on LPS-induced septic ileus through inhibition of inflammation in the muscularis propria. These inhibitory effects on the pro-inflammatory response may be partially derived from anti-inflammatory cytokine interleukin-10 induction.